This invention relates to welding electrodes and particularly relates to a welding electrode wound on a dispensing spool having a plurality of current conducting terminals for supplying a maximum welding current to the electrode for the purposes of welding, and the method of making such electrode.
A welding electrode wire consists of an elongated metal wire core having a welding flux coating provided on its outside surface. The flux coating is made of a relatively flexible compound so that the electrode wire can be wound on a spool for dispensing during use. In the welding process, a high current must be passed through the electrode wire and the work piece in order to provide the required energy for fusing the metal of the metal wire core to the work piece. Since the flux is made of a electrically non-conductive or highly resistive material, it has been problematic in providing the high current efficiently from one end of the inner end of the electrode through its entire length to the free end therein in the welding operation. Due to the relatively long length of metal wire core, the supply current must pass through, a considerable amount of the supply current is inherently lost through leakage and the intrinsic resistance in the metal wire core. Therefore, the current from the supply is not efficiently utilized resulting often in the formation of unsatisfactory welds.
In order to obviate the above problem, one attempt has been made by providing a longitudinal groove in the flux coating extending over the entire length of the electrode wire. The longitudinal groove exposes the metal wire core such that the welding current can be directly supplied to the metal core at any selected point and as close to the free end of the electrode as possible so as to provide the needed high current for forming a satisfactory weld. However, the main drawback of such a construction is that since the flux coating is not uniformly provided over the circumferential surface of the metal wire core due to the existence of the longitudinal groove, in the welding operation the flux is not uniformly provided to the welding pool resulting in the formation of a weak weld. Moreover, the flux coating tends to scatter away from the metal wire core in use when heat is generated at the metal wire core. Thus, insufficient flux is being provided to the weld. This is due to that the elongated longitudinal groove has weaken the cohesion of the flux material coated on the metal wire core.